Heating system for a vehicle

ABSTRACT

A heating system for a vehicle includes a reformer arrangement for producing hydrogen from a hydrocarbon/mixed material mixture, a burner arrangement for reception of hydrogen produced in the reformer arrangement and combustion thereof, and a heat exchanger arrangement for transferring combustion heat produced in the burner arrangement to a heating medium.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

BACKGROUND OF THE INVENTION

[0003] The present invention relates to a heating system for vehicles.

TECHNICAL FIELD

[0004] In modern motor vehicles, there is, firstly, on the basis ofvarious technical requirements and, secondly, on the basis of theincreased expected comfort, increasingly the need to provide anauxiliary heating system that is able to produce heat essentiallyindependently of the operation of a drive assembly, i.e., for example,an internal combustion engine, through combustion of a fuel/air mixture.All the same, it is also required, for cost reasons, to design vehiclesand various systems provided therein as far as possible in such a mannerthat, by fusing together functions and components, a more favorablesystem is obtained which, in particular, is also improved in respect tothe structural space taken up.

SUMMARY OF THE INVENTION

[0005] The object of the present invention is to provide a heatingsystem for a vehicle that realizes efficient heating of various systemregions of a vehicle in a structurally simplified manner.

[0006] According to the present invention, this object is achieved by aheating system for a vehicle, comprising a reformer arrangement forproducing hydrogen from a hydrocarbon/mixed material mixture, a burnerarrangement for reception of hydrogen produced in the reformerarrangement and combustion thereof, and a heat exchanger arrangement fortransferring combustion heat produced in the burner arrangement to aheating medium.

[0007] An essential feature of the present invention is for one systemregion of a vehicle, namely a reformer arrangement in which hydrogen isprovided, for example for operation of a fuel cell, also to form part ofa heating system, namely by virtue of the hydrogen that is provided bythe reformer arrangement being burned and it being possible to use thecombustion heat produced as a result to heat various system regions ofthe vehicle. To this extent, the auxiliary heating function oradditional heater function can therefore be integrated in a reformersystem, and it is not necessary to provide a separate auxiliary heatingunit.

[0008] Since, in the design according to the invention of a heatingsystem, combustion of the hydrogen provided in the reformer arrangementtakes place in the burner arrangement, it is advantageous if a flametrap is arranged between the reformer arrangement and a combustionchamber of the burner arrangement. With combustion taking place in theburner arrangement, a spark ignition or reignition in the reformerarrangement is therefore effectively prevented even when these twosystem regions are situated comparatively close to each other.

[0009] According to a further advantageous aspect, feeding means can beprovided for feeding hydrogen produced in the reformer arrangement to atleast one further hydrogen-consuming system. In this case, the at leastone further hydrogen-consuming system, for example, may comprise anexhaust-gas aftertreatment system for an internal combustion engineand/or a fuel cell.

[0010] In order to be able to use the reformer arrangement veryefficiently in particular when additional hydrogen consumers areprovided in a vehicle, it is proposed that the feeding means comprisedistributing means for distributing hydrogen produced in the reformerarrangement to the burner arrangement and the at least one furtherhydrogen-consuming system.

[0011] Since, in an arrangement of this type, differenthydrogen-consuming system regions are to be activated in differentoperating phases while other system regions are not to be supplied withhydrogen, provision may furthermore be made for the ratio ofdistribution of the distributing means to be changeable.

[0012] In an alternative embodiment which is structurally very simple torealize and also easy to operate, provision may be made for the feedingmeans to connect an outlet region of the burner arrangement to the atleast one further hydrogen-consuming system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention will be described in detail below usingpreferred embodiments and with reference to the attached drawings, inwhich:

[0014]FIG. 1 shows a schematic longitudinal sectional view of a heatingsystem according to the invention;

[0015]FIG. 2 shows a cross-sectional view of the heating systemillustrated in FIG. 1 in the region of the burner arrangement;

[0016]FIG. 3 shows an illustration in the manner of a block diagram ofone manner of designing a heating system according to the invention andof integrating it in a vehicle;

[0017]FIG. 4 shows a view corresponding to FIG. 3 of an alternativemanner of designing it.

DETAILED DESCRIPTION OF THE INVENTION

[0018] In FIG. 1, a system according to the invention is referred to ingeneral by 10. This system can essentially be divided into threeregions, namely a reformer arrangement 12 situated in the upstreamregion, a burner arrangement 14 following it downstream, and a heatexchanger arrangement 16 arranged following the burner arrangement 14.In an embodiment which is preferred because of the simple design, all ofthese system regions 12, 14, 16 can be accommodated in a single, tubularhousing region 18.

[0019] The reformer arrangement 12 comprises a catalytic converter 20(illustrated symbolically), in which a mixture, which is symbolized bythe arrow P₁, of air and hydrocarbon, for example diesel fuel, isdecomposed, if appropriate with the addition of water or a purewater/hydrocarbon mixture, so that a gaseous mixture which contains acomparatively high content of hydrogen leaves the reformer arrangement12. To produce the mixture which is to be decomposed, the reformerarrangement 12 can have an evaporator arrangement which can be preheatedor to which starter material which has already been preheated can alsobe fed to produce the mixture. The catalytic converter 20 can also beassigned a heating device in order to bring it up to the temperaturewhich is required for the catalysis and which lies in the region of 320°C. when diesel fuel is used as the hydrocarbon.

[0020] The gas leaving the reformer arrangement 12 enters via a flametrap 22 into the burner arrangement 14 and into a combustion chamber 24thereof. Combustion air is furthermore fed into this combustion chamber24 via an air-feeding line system 26, which is illustrated in FIG. 2.This air-feeding line system 26 comprises a line region 28 which feedsin air, symbolized by the arrow P₃, from the outside, an annulardistributing line region 30 and a plurality of air input sections 32leading into the combustion chamber 24. This results in an input whichis as uniform as possible of the air which is to be burned together withthe hydrogen passed into the combustion chamber 24. In order to ignitethe mixture of air and hydrogen and therefore to trigger the combustion,an ignition element 34 which can have a spiral-type filament or the likecan be provided.

[0021] The combustion products which are produced in the combustion inthe burner arrangement 14 and are generally present in gaseous formtransport the heat, which is likewise produced in the combustion, towardthe heat exchanger arrangement 16. The latter comprises a heat exchangerbody 36 (illustrated only in principle) into which medium, for exampleair or, if appropriate, also liquid, which is to be heated is fed via aninlet region 38 and from which this medium is drawn off again via anoutlet region 40.

[0022] The combustion products which leave the burner arrangement 14flow through a plurality of flow ducts 42 leading through the heatexchanger body 36, so that a transfer of heat to the medium which flowsthrough the heat exchanger body 36 and is to be heated can take place.As indicated by the arrows P₂, the combustion products and combustionexhaust gases then leave the heat exchanger arrangement 16 and can befed, for example, into an exhaust-gas system provided in the vehicle orcan be made further use of in a manner as still to be described below.

[0023] The system that is illustrated in FIGS. 1 and 2 therefore makesit possible to use the hydrogen gas produced in a reformer arrangement12 as a fuel, by means of combustion, for example in order, in anauxiliary heating mode, to heat air which is to be fed into a vehicleinterior, or in order, in a preheating mode for preheating a driveassembly, to heat the cooling medium thereof and therefore to bring thedrive assembly up to a temperature suitable for the following operation.

[0024] The integration of a system 10 of this type, as is shown in FIGS.1 and 2, in a vehicle system will be described below with reference toFIG. 3. An internal combustion engine used as drive assembly is referredto there by the reference number 44. The combustion exhaust gasesthereof are after-treated in an exhaust-gas after-treatment system 46 inorder to reduce the emission of pollutants. Said exhaust-gasafter-treatment system generally comprises a catalytic converter (notillustrated).

[0025]FIG. 3 furthermore shows the heating system 10 according to theinvention containing the reformer arrangement 12, the burner arrangement14 and the heat exchanger arrangement 16 following one another in thedirection of flow. As again symbolized by the arrows P₁, the reformerarrangement 12 receives the mixture of hydrocarbon and further mixedmaterial, for example air and/or water, which is to be decomposed. Thismixture is decomposed, as described above, and the hydrogen produced inthe process can be burned with air, symbolized by the arrow P₃, beingadded. The heat which is produced in the process is transferred in theheat exchanger arrangement 16 to a medium which then heats a systemregion 48, which is to be heated, i.e. a vehicle interior, for example.In the combustion mode of the burner arrangement 14, the combustionexhaust gases which leave the heat exchanger arrangement 16 and whichwill still have a comparatively high temperature particularly if themedium which is to be heated circulates only to a limited extent, if atall, then enter at this high temperature into the exhaust-gas ductingsystem 50 of the vehicle. These combustion exhaust gases then continueto enter into the exhaust-gas after-treatment system 46 and flow therearound the catalytic converter acting to after-treat exhaust gas. In aphase in which the internal combustion engine 44 has not yet been putinto operation and therefore the entire exhaust-gas ducting system 50has a comparatively low temperature, it can therefore be ensured, bypreheating the exhaust-gas after-treatment system 46, in particular thecatalytic converter, that from the beginning of the operation of theinternal combustion engine 44 this exhaust-gas after-treatment system 46is able in the required manner to convert the exhaust gases emitted bythe internal combustion engine 44 and, in particular, to reduce thecontent of nitrogen oxides.

[0026] In order, in an operating phase, in which the internal combustionengine 44 has already been put into operation and to this extent iseffective, firstly, as a heat source for heating air which is to be fedinto the vehicle interior, but, secondly, the exhaust-gas ducting system50 and therefore also the exhaust-gas after-treatment system 46 are alsokept at the required operating temperature by the combustion exhaustgases of the internal combustion engine 44 that transport a considerableamount of thermal energy, to be able to ensure a further improvement inthe emission control, it is possible to operate the heating system 10according to the invention in such a manner that although the reformerarrangement 12 produces hydrogen, the burner arrangement 14 isdeactivated, i.e. the hydrogen fed into it is not burned there and, ifappropriate, is also not mixed with additional air. The gases leavingthe reformer arrangement 12 and containing a relatively large quantityof hydrogen then flow without further action through the heat exchangerarrangement 16 and pass into the exhaust-gas ducting system 50 andtherefore also into the exhaust-gas after-treatment system 46. Aconsiderable quantity of hydrogen is therefore fed into the exhaustgases of the internal combustion engine 44 and, in order to reduce thenitrogen oxide content, can be converted both with NO₂ and also with NOin order to produce N₂ and H₂O.

[0027] It can be seen from the preceding description that by dividing upthe overall system in the vehicle the heating system 10 according to theinvention can be operated in diverse ways and can thus be effective indifferent operating phases in which there are also differentrequirements, i.e. the requirement for preheating various systemregions, on the one hand, and, if appropriate, the provision of hydrogenfor further processing, on the other hand.

[0028] A further overall system, into which the heating system accordingto the invention can be divided in order to increase the overallfunctionality, is shown in FIG. 4. The drive assembly 44, theexhaust-gas ducting system 50 thereof and the exhaust-gasafter-treatment system 46 can also be seen here again. The heatingsystem 10 is now provided with a valve arrangement 52 between thereformer arrangement 12 and the burner arrangement 14. The gas mixtureleaving the reformer arrangement 12 can be fed through this valvearrangement 52 via a line branch 54 directly into the exhaust-gasducting system 50 of the internal combustion engine 44, can be conductedvia a line region 56 to the burner arrangement 14 or can be conductedvia a line region 58 to a fuel cell system, which is referred to ingeneral by 60. This fuel cell system 60 can comprise a gas-cleaningsystem 62 connected upstream of the actual fuel cell 64. Particularlywhen “low-temperature fuel cells” which operate in a temperature rangeof approximately 80° C. are used, it is necessary to enrich the gasmixture leaving the reformer arrangement 12 with hydrogen and to reducethe content of carbon monoxide as far as possible. For this purpose,gas-cleaning systems 62 of this type generally likewise have catalyticconverters which operate in a temperature range of 200° C. to 500° C.This means that, before the fuel cell 64 is put into operation, at leastthe gas-cleaning system 62 has to be correspondingly preheated, andpreferably the fuel cell 64 itself also has to be brought up to asuitable operating temperature. This can be realized in the systemaccording to the invention, which is illustrated in FIG. 4, as follows:

[0029] In a phase before the fuel cell 64 is put into operation, firstof all, with the internal combustion engine 64, for example, notactivated, the gas mixture leaving the reformer arrangement 12 isconducted through the valve arrangement 52 into the burner arrangement14 and burned there. These combustion exhaust gases then leave theburner arrangement 14 and, after flowing through the heat exchangerarrangement 16, pass to a further valve arrangement 66 which, in thisphase, is switched in such a manner that the combustion exhaust gases ofthe burner arrangement 14 are fed into the line region 58 upstream ofthe gas-cleaning system 62. Of course, the heat exchanger arrangement 16may also be active in this operating phase in order to be effective inan auxiliary heating mode by heating a heating medium, for example airwhich is to be fed into a vehicle interior. The heated combustionexhaust gases which flow into the line region 58 also flow through thegas-cleaning system 62 and, if appropriate, also the fuel cell 64, inorder also to heat them, and then pass via a line region 68, forexample, into the exhaust-gas ducting system 50 of the internalcombustion engine 44 in order furthermore also to preheat the catalyticconverter of the exhaust-gas after-treatment system 46 at least with theresidual heat which has remained.

[0030] If the gas-cleaning system 62 is at a suitable operatingtemperature, it can be ensured, by switching over the valve arrangement52, that at least part of the gas mixture leaving the reformerarrangement 12 now flows into the line region 58 in order therefore tobe able to provide, using the gas-cleaning system 62, a gas or gasmixture which is enriched in a suitable manner with hydrogen and isfreed from other impurities for the fuel cell 64 and in order to be ableto put the fuel cell 64 into operation. In this operating phase, thevalve arrangement 66 can furthermore be switched in such a manner thatthe combustion exhaust gases leaving the burner arrangement 14 and theheat exchanger arrangement 16 flow into the line region 54 leading tothe exhaust-gas ducting system 50 of the internal combustion engine 44and no longer flow into the line region 58 leading to the fuel cellsystem 60. The fuel cell 64 can then be operated to produce electricenergy, for example in order to be able to operate a drive assembly oran auxiliary drive assembly or in order to be able to provide electricenergy for the vehicle electric system. In this operating phase, theinternal combustion engine 44 can also be operated at the same time, inwhich case the valve arrangement 52 can then be switched in such amanner that the gas mixture leaving the reformer arrangement 12 isdistributed to the two line regions 54 and 58 and gas mixture no longerflows into the line region 56. This has the effect that, firstly,hydrogen is provided for operating the fuel cell 64, and, secondly,hydrogen is available for feeding into the combustion exhaust gases ofthe internal combustion engine 44 and therefore for improvedafter-treatment of the same in the exhaust-gas after-treatment system46. If, in this operating phase, heat is additionally to be provided bythe burner arrangement 14, for example in order to fulfill an“additional heater function”, then the valve arrangement 52 can beswitched in such a manner that hydrogen-containing gas mixture isconducted with the desired ratio of distribution into all three lineregions 54, 56, 58.

[0031] It is self-evident that various changes to the system shown inFIG. 4 may be undertaken. The combustion exhaust gas leaving the burnerarrangement 14 could therefore, as indicated by a broken arrow, be feddirectly into the line region 58 by provision of appropriateswitching-over means in order to be able to avoid heat losses which mayoccur in the heat exchanger arrangement 16. The line region 54 couldalso be omitted, so that if hydrogen is to be fed into the exhaust-gasducting system 50 of the internal combustion engine 44 for the purposeof improved emission control in the exhaust-gas after-treatment system46, the valve arrangement 52 is switched in such a manner that at leastpart of the hydrogen-containing gas mixture flows out of the reformerarrangement 12 into the line region 56, in which, however, the burnerarrangement 14 is deactivated at the same time and this gas mixture cantherefore pass into the exhaust-gas ducting system 50 by appropriateswitching of the valve arrangement 66. It is furthermore possible toheat the gas-cleaning system 62 and/or the fuel cell 64 and/or thecatalytic converter 20 of the reformer arrangement 12 using the heatexchanger arrangement 16, i.e., for example in the case of thegas-cleaning system 62, not to have the combustion exhaust gases of theburner arrangement 14 flowing directly through it, but rather totransfer heat to this gas-cleaning system 62 by means of a heatingmedium circulating between the heat exchanger arrangement 16 and thegas-cleaning system 62. Of course, the same also applies to the othersystem regions which have been discussed, for example the fuel cell 64.

[0032] In place of the valve arrangement 52 which can be seen in FIG. 4and ensures that a distribution of the gas mixture leaving the reformerarrangement 12 can take place in certain operating phases, in an optimummanner in each case for these operating phases, and therefore thatcertain line regions can be completely closed, it is basically alsopossible to provide an arrangement which specifies a fixed ratio ofdistribution, for example if, in a certain, specified system, the gasquantities which are to be fed into the line region 54 and into the lineregion 58 are always to be in a certain quantitative proportion to oneanother. For example, in this case a pipe with a divided cross sectioncan ensure an appropriate ratio of distribution.

[0033] According to a further or additional aspect, it is possible, inthe systems 10 according to the invention which are illustrated above,not to conduct some or all of the hydrogen-containing gas mixtureleaving the reformer arrangement 12 directly to a hydrogen-consumingsystem, but rather to conduct it into an intermediate store where it canbe held under pressure. Thus, for example in the system illustrated inFIG. 3, a store of this type could be positioned between the reformerarrangement 12 and the burner arrangement 14, it then being possible toblock off said store toward the reformer arrangement 12 and/or towardthe burner arrangement 14 by respective valve arrangements or the like.In the system of FIG. 4, a store of this type could be positionedbetween the reformer arrangement 12 and the valve arrangement 52. In anarrangement of this type, it is then possible to operate the reformerarrangement 12 irrespective of the actual hydrogen requirement, so that,in phases in which only a small amount of hydrogen is required, if any,the store is charged, and in phases in which more hydrogen is required,the store is discharged. For example, in a phase requiring a very largeamount of hydrogen, a hydrogen-consuming system can be fed both from thestore and also directly from the reformer arrangement 12. It is thuspossible also to feed hydrogen-consuming systems in an operating phasein which, for example, the temperatures required for carrying out thecatalytic reaction are not yet present in the reformer arrangement 12.Furthermore, it is possible to operate the reformer arrangement 12 withoptimum operating parameters which are independent of the actualhydrogen arrangement, in order to increase the efficiency thereof.

What is claimed is:
 1. A heating system for a vehicle, comprising: areformer arrangement (12) for producing hydrogen from ahydrocarbon/mixed material mixture, a burner arrangement (14) forreception of hydrogen produced in the reformer arrangement (12) andcombustion thereof, and a heat exchanger arrangement (16) fortransferring combustion heat produced in the burner arrangement (14) toa heating medium.
 2. The heating system as claimed in claim 1, wherein aflame trap (22) is arranged between the reformer arrangement (12) and acombustion chamber (24) of the burner arrangement (14).
 3. The heatingsystem as claimed in claim 1, wherein hydrogen feeding means (14, 16;52, 54, 58) are provided for feeding hydrogen produced in the reformerarrangement (12) to at least one further hydrogen-consuming system (46,60).
 4. The heating system as claimed in claim 3, wherein the at leastone further hydrogen-consuming system (46, 60) comprises an exhaust-gasafter-treatment system (46) for at least one of an internal combustionengine (44) and a fuel cell (60).
 5. The heating system as claimed inclaim 3, wherein the hydrogen feeding means (52, 54, 58) comprisehydrogen distributing means (52) for distributing hydrogen produced inthe reformer arrangement (12) to the burner arrangement (14) and the atleast one further hydrogen-consuming system (46, 60).
 6. The heatingsystem as claimed in claim 5, wherein the ratio of distribution of thehydrogen distributing means (52) can be changed.
 7. The heating systemas claimed in claim 3, wherein the hydrogen feeding means (14, 16)connect an outlet region of the burner arrangement (14) to the at leastone further hydrogen-consuming system (46).